complex defines..

[designer]

Hi all,
I have a define like
#define N_THREADS 4
I want to have another define depending on N_THREADS which should be
log (N_THREADS) to the base 2.
In the above example it becomes 2.Is there any such way...
Thanks,
Vittal

 

[Kevin Neilson]

designer wrote:

Hi all,
I have a define like
#define N_THREADS 4
I want to have another define depending on N_THREADS which should be
log (N_THREADS) to the base 2.
In the above example it becomes 2.Is there any such way...
Thanks,
Vittal
You can sort of do this with defines, but it's messy and much better to

do it with parameters and constant functions, which most tools support
now. As in:

parameter N_THREADS=4;
parameter log2_N_THREADS=clog2(N_THREADS);

....

function clog2(...

-Kevin

 

On Sep 13, 12:19 am, "arko" <a...@winnet.com> wrote:

Systemverilog-2008 will add a standard system-task $clog2(), which returns
log2() of its argument.

This was actually added in Verilog-2005, along with the ability to use
this system function and certain others in constant expressions.

Unfortunately, no tools today support it yet.  And you can bet industrywide
support is
years away...

I wouldn't be surprised. SystemVerilog has added an immense number of
features to be implemented, and the 2009 draft standard adds more.
This Verilog feature probably isn't very high priority for most
implementors.